A variety of indications require rehabilitation phases requiring different functions. Most orthopedic devices, inclusive of braces and supports, are arranged for only a single indication and lack the flexibility to be easily modified to the rehabilitation demands of an individual.
Osteoarthritis of the knee is a common cause of musculoskeletal pain and disability of the knee joint. The ends of the femur and tibia are covered with smooth articular cartilage, and meniscal cartilage is located between the ends of the femur and tibia. Osteoarthritis is a slowly progressive disease of the knee joint in which the articular cartilage and subchondral bone gradually wears away, and then progresses into surrounding bone, tissues, synovial fluid. The cartilage may have areas more prone to thinning or complete loss. Isolated loss may result from isolated trauma or may be to chronic wear and tear of the knee.
One of the recognized causes of osteoarthritis initiation is a cartilage lesion from isolated trauma to the knee. Articular cartilage lesions of the knee are a common cause of pain and functional disability. The defects lead to progressive symptoms and degeneration due to either slowness or the inability of the cartilage to heal. Nonoperative rehabilitation is often unsuccessful, and additional treatment may be required to alleviate symptoms since articular cartilage defects do not heal spontaneously. These complications present challenges for individuals who are young and active, and do not otherwise have gross degenerative defects of the knee but have only focal cartilage defects.
Over the last decade, surgeons and researchers have elaborated on surgical cartilage report to treat these lesions. Though these solutions do not perfectly restore articular cartilage, some latest technologies have provided more promising results in repairing cartilage from traumatic injuries or chondropathies (disease of the cartilage). These treatments are particularly targeted at patients who suffer from articular cartilage damage. The treatments provide pain relief while slowing down the progression of damage or considerably delaying joint replacement surgery. Articular cartilage repair treatments help patients return to their original lifestyle by regaining mobility.
Though different articular cartilage procedures differ in surgical techniques, they all share the aim to repair articular cartilage while keeping options open for alternative treatments in the future. One of the promising procedures entails microfracture surgery for repairing articular cartilage defects that involves creating tiny fractures in the underlying bone to cause new cartilage to develop. The technique involves debridement through a calcified cartilage layer followed by perforation of the subchondral bone with surgical awls. A bone marrow clot is formed at the base of the prepared lesion. The clot contains cells that differentiate into cartilage over time (14-18 months) following surgery.
After surgery, the blood clot is delicate and must be protected. The clot takes 8-15 weeks to convert to fibrous tissue and turns into fibrocartilage about 4 months after surgery. Fibrocartilage replaces hyaline cartilage existing at the location prior to the chondral defect and is not as mechanically sound as hyaline cartilage. Because fibrocartilage is more dense and less durable to withstand daily activities, and there is a higher risk of breaking down than hyaline cartilage.
In view of these factors, rehabilitation from microfracture surgery may last multiple months as the fibrocartilage forms. Rehabilitation includes several phases depending on the level of healing: (1) non-weightbearing (weeks 0-6), (2) progressive strengthening and loading (weeks 6-12), (3) neuromuscular retraining (weeks 12-24), and (4) return to activity (weeks 24 and beyond). Within the retraining and return to activity protocols, different sport levels include: low-impact sports (2-3 months), (5) higher impact sports (4-5 months), and (6) high-impact pivotal sports (6-8 months).
Rehabilitation following any cartilage repair procedure is paramount for success of any cartilage resurfacing technique. Rehabilitation is long and demanding. The main reason for the duration of rehabilitation is the cartilage cells must adapt and mature into repair tissue. Cartilage is a slow adapting substance, and where muscle takes approximately 35 weeks to fully adapt itself, cartilage only undergoes 75% adaptation in 2 years. If rehabilitation is too short, the cartilage repair might be under too much stress, causing the repair to fail.
An unloading brace of the type described in U.S. Pat. No. 7,198,610 may be used during the partial weightbearing phase and onwards until full recovery has been achieved. The unloading brace reduces the load applied to the clot and mitigates or prevents damage as the clot coverts to fibrous tissue. While crutches may likewise reduce weightbearing, an unloading brace permits the individual to use the affected limb, which at least helps keep the joint flexible, increases the range of motion, and prevents surrounding muscles from atrophy.
An unloading brace applies a gentle force design to reduce the pressure on the affected part of the knee, particularly where the lesion is formed, resulting in reduction in pain. The force unloads pressure on the affected part of the knee and orients the knee so the affected part is not further aggravated.
There is evidence that cartilage damage in chondral lesions may eventually lead to developing osteoarthritis, regardless of the surgical treatment. There is some indication for continued an unloading brace, even after the clot has fully developed into fibrocartilage, particularly in view of its inherent weakness compared to hyaline cartilage.
From the foregoing, there is a need for an orthopedic device arranged for providing protective support for regeneration of knee cartilage after surgical repair procedures. The need is further accentuated by providing a solution adaptable for different treatment stages during the healing process and rehabilitation of cartilage repair.